In the fuel burner control art it is normally necessary to sequence a blower supplying combustion air, the ignition source, and the main burner source of fuel in a prescribed series of timed intervals. This sequencing or programming can be accomplished by a number of different expedients.
In large fuel burner control systems the sequencing of the combustion air, ignition, and main burners is accomplished by programmers that have motor driven cam switches that operate in a timed sequence compatible with the particular burner. In smaller burners this can be accomplished by using electronic types of timing devices. Typically the electronic types of timing devices use a single timing circuit for each of the timed intervals required in the burner sequence. Typically, each timing interval will require an individual electronic timing circuit and these timing circuits will be sequenced so that a burner is properly operated. The more timing intervals required, obviously the more electronic components are required, and naturally the more expensive the device then becomes. A typical burner control device using electronic timing having a single safety interval is disclosed in U.S. Pat. No. 3,619,097 to Clay. In the Clay patent a pair of capacitors forming a voltage divider network provide a safety timing function and are used solely for that purpose. The additional functions required in the device require additional electronics in order to accomplish the programming and timing functions.